<!DOCTYPE html>
<style>
  body::first-line { color: purple; }
</style>
<body style="width: 0; color: red"><span id="x" style="visibility: hidden">This is some text</span>
  <script type="text/javascript">
    document.body.offsetWidth;
    document.getElementById("x").style.visibility = "visible";
    document.body.style.color = "green";
  </script>
</body>
